To better understand the exact magnitude of the lift force A new experimental technique has been developed to study the as well as its mechanism, we performed a systematic study electrokinetic lift force acting on an electrically charged particle of this force with our microcollider (or surface collision moving parallel to a surface in a polar liquid. It is based on the apparatus) (10), which is capable of accurately controlling observation of the normal movement of a particle close to a wall the shear rate and measuring the changes in particle depth in a wall shear flow. The experimental results show that the force as a function of time. We also developed a new theory (later increases with increasing shear rate and decreasing solution condenoted as Warszynski-van de Ven theory or W-V theory) ductivity. These findings are consistent with previously reported emphasizing the nonzero normal hydrodynamic stress which data and confirm the existence of an electrokinetic lift force that is was found to be orders of magnitude larger than the Maxwell difficult to detect because of its small magnitude. The experimental results are compared with various theoretical predictions. The stress and is the main contribution to the lift force. The comparisons show that the lift force calculated by most electrokitheory will be discussed in detail in a future publication netic theories is not correct. Two new recently developed theories (11). Recently another theory was developed independently were applied to interpret the data, and reasonably good agreement by Cox to calculate the lift force (12). It also treats the with experimental results was found.